Array pattern modification



May 4, 1965 A. E. BLUME 3,182,325

ARRAY PATTERN MODIFICATION Filed Sept. 21, 1960V A l /9v y \/6/ V 6) i Vm Vm I l 5 LLA-J Pm IN V EN TOR.

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/f/is Aorrley United States Patent O M 3,'lti225 ARRAY PATTERN MDFHCATLN Alan E. Blume, Ballston Lake, NX., assigner to General Electric Company, a corporation of New Yorir Filed Sept. 2l, 1966, Ser. No. 57,429 ill Claims. (Qi. 34E-mtl) This invention relates to an array pattern modication and, more particularly, to an array for producing a directional beam pattern of wave energy. ln the following discussion, the term radiation is intended to cover both electromagnetic and acoustic wave energy.

It is well lmown that a directed beam of wave energy, such as Ia conventional pencil beam, may be obtained from an array by varying the magnitude of the signal supplied to the individual elements of the array while simultaneously varying the phase of the signal supplied to each element linearly; that is, in direct proportion to the spacing of the individual elements from the center of the array. The amount of the slope of the linear phase of the signal supplied to each element determines the angular position of the beam, whereas the variation of the magnitude of the signal together with the linear phase slope determines the shape of the beam. The beam obtained by this method can be similar to that generally obtained with a simple dipole or horn feed at the focus of a paraboloidal reflector. This latter type of radiator generally has a main beam that is broader and side lobes that are lower than would be produced by an array of the same size with uniform excitation magnitude and constant phase. lt will be noted, then, that if the excitation magnitude is varied across the array, the total amount of power available for the production of the beam is limited as compared with the situation where the excitation magnitude is not varied. There fore, prior array systems are not capable of supplying full power to each element of the array since the excitation magnitude must vary in order to produce a beam with characteristics similar to those of a paraboloidal reiiector with .a dipole or horn feed at its focus.

It is, therefore, an object of the invention to provide an array capable of radiating a conventional pencil beam of radiation similar to the beam of a conventional paraboloidal reiiector without sacrificing power handling capabilities of any of the array elements.

It is a further object of the invention to provide an improved array arrangement for producing a pencil beam with increased power.

lt is still another object of the invention to provide a simpler and more dependable directional beam array arrangement.

lt is still another object of the invention to provide an array for producing a directional radiation beam pattern having reduced side lobe radiation levels.

Briefly stated, `in accordance with one aspect of the invention, an array is energized uniformly, thereby permitting maximum power to be delivered to each individual element. The phase of the excitation signal supplied to each element of the array is varied linearly with the spac-` ing of each element from the center of the array for the purpose of directing the position of the main beam of the radiation pattern. In addition to this linear phase deviation, selected elements, chosen symmetrically about the center of the array, are phase reversed; that is, the polarity of the signal supplied to the selected elements, which have a phase linearly deviating in accordance with the distance from the center of the array, is in addition reversed. An arrayexcited in this manner provides maximum power excitation for all elements in the array and further, with proper `selection of the elements to be phase reversed, will have a radiation pattern with side lobes lower than Patented May 4i, 1965 that of an array without phase reversed elements. The phase reversal of selected elements may be easily accomplished. With certain types of elements, such as dipoles, this may be done by reversing the connection of the leads to the selected elements. With other types, such as waveguide horns, a 180 twist in the waveguide or a 180 delay section in the waveguide may be used.

The invention, both as to its organization and operation together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings, in which FIG. 1 is a diagrammatic illustration showing a plurality of radiating elements arranged to form a linear array;

FIG. 2 shows a curve of the electric eld strength of the radiation of the array of FIG. l; i

FIG. 3 is a diagrammatic illustration showing a linear array constructed according to the teachings of the invention;

FIG. 4 shows a plurality of curves to explain the operation of the invention; and

FIG. 5 shows additional curves which further explain the operation of the invention.

Referring to FIG. 1, a linear array is shown having a plurality of elements 11 symmetrically spaced about the center 12 or the array. The elements may be any type of radiating structure, such as dipoles, waveguide horns, dielectric rods, slotted waveguides, transducers, or any type of structure suitable for transmitting or receiving electromagnetic or acoustic radiations. Correspondingly, the energy sources and the feed structures for supplying the elements with radiating energy may take any form suitable 4for use with the type of element chosen. For convenience, the elements are numbered successively from the array center. The elements may be connected to a source of energy by any suitable means. The means for varying the phase of the excitation signal supplied to each element is identified by the letter P and the .corresponding element number. For example, the phase varying means connected to element 1 is identified as P1, the phase varying means connectedto element 2 is identified as P2, etc. Each of the phase varying means. may be connected to a suitable source of energy S which provides the uniform excitation signal. The spacing between the individual elements is shown as the dimension d where the units of d are in terms ofwa'velengths. The array shown has a total of m elements on either side of the array center. The signal supplied to each element of the array is maintained at a uniform magnitude, and the phase of` the signal to each element is varied in proportion to the algebraic distance from lthe centerof the array to the particular element; that is, the array is energized with a linear phase deviation. The radiation pattern of such an 4array is often plotted in terms of the electric Vfield strength E and the angle 0 measured from broadside. An example of the plot of the iield strength of an array such as shown in FIG. l is shown in FIG. 2.

Referring to FIG. 2, `the electric eld `strength E of the main beam is shown by the curve :at 15, and the electric field strength of successive side lobes is shown at 16, 17, 18, 19. A11 .array of a type shown in FIG. 1 and having a beam pattern such as shownin FIG. 2 will have a tirst side lobe iield strength approximately 13 db below the electric field strength of the peak of the main beam. Within the fundamental regionof the main beam pattern, which extends to proximately equal to 1/0 of the total number of elements in the array, and choosing these elements in a region approximately 80% of the distance from the center of the array to the edge of the array, and reversing the phase of the energization signal to these elements. The phase reversal may be accomplished by reversing the connections of the energy source, or,`in some cases, by introducing a 180 phase delay.

lt will be obvious to those sldlled in the art Ythat many variations and modifications of the disclosed array system may be made Without departing from the spirit and scope of the invention. For example, the array may be a planar array, the linear array described being chosen only for simplicity o f illustration. Therefore, -this invention is to be considered as limited only in accordance with the teachings thereof as set forth in the claims appended hereto.

What I claim as new and desire to secure by letters Patent of the -United States is: i

l. An array comprising a plurality of elements, means for connecting a uniform magnitude excitation signal to the elements of said array for permitting maximum power to be delivered to each element of the array, said uniform magnitude excitation signal having a linearly Varying phase deviation for directing the position of the main beam of the radiation pattern, said connecting means being arranged to reverse the phase of the phase deviated signal to selected ones of the elements that are equidistantly disposed about the center of said array for reducing the side lobes of the radiation pattern.

2. An array comprising a plurality of elements, means for connecting a uniform magnitude excitation signal to the elements of said array for permitting maximum power to be delivered to each element of the array, said uniform magnitude excitation signal having a linearly varying phase deviation for directing the position of the main beam of the radiation pattern, said connecting means being arranged to reverse the phase of the phase deyiated signal to selected ones of the elements that are equidistantly disposed about the center of said array for reducing the side lobes of the radiation pattern, the total number of said selected ones of said elements being less than 1A() of the total number of elements in the array.

3. An array comprising a plurality of elements, means for connecting a uniform magnitude excitation signal to the elements of said array for permitting maximum power to be delivered to each element of the array, said uniform magnitude excitation signal having a linearly varying phase deviation for directing the position of the main beam of the radiation pattern, said connecting means being ar ranged to reverse the phase of the phase deviated signal to selected ones of the elements that are equidistantly disposed about the center of said array for reducing side lobes of the radiation pattern, the total number of said selected ones of said elements being less than 1/10 of the total number of elements in said array, the distance from the center of the array to any one of said selected ones of said elements being at least 50% of the distance from the center of the array to the edge of said array.

4. An array comprising a plurality of elements, means for connecting a uniform magnitude excitation signal with a given phase deviation to the elements of said array, said connecting means being arranged to reverse the phase of the phase deviated signal to selected ones of the elements that are equidistantly disposed about the center of said array, the total number of said selected ones of said elements being substantially equal to 1/20 of the total number of elements in said array, the distance from the center of said array to any one of said selected ones of said elements being substantially 80% of the distance from the center of said array to the edge of said array.

5. A linear array comprising a plurality of elements with an equal number of elements disposed on each side of the center of said array, means for connecting a uniform magnitude excitation signal to the elements of said arrayfor permitting maximum power td be delivered to each element of the array, said uniform magnitude excitation signal having a linearly Varying phase deviation for directing the position of the main beam of the radiation pattern, said connecting means being .arranged to reverse the phase of the phase deviated signal to selected ones of the elements that are equidistantly disposed on each side of the center of said array for reducing the side lobes of the radiation pattern.

6. A linear array comprising a plurality of elements with an equal number of elements disposed on each side of the center of the array, means for connecting a uniform magnitude excitation signal to the elements of said array for permitting maximum power to be delivered to each element of the array, said uniform magnitude excitation signal having a linearly varying phase deviation for directing the position of the main beam of the radiation pattern, and connecting means being arranged to reverse the phase of the phase deviated signal to selected ones of the elements that are equidistantly disposed on each side of the center of said array, for reducing the side lobes of the radiation pattern, the total number of said selected ones of said elements being less than 1/10 of the total number of elements in said array.

7. A linear array comprising a plurality of elements with an equal number of elements disposed on each side of the center of said array, means for connecting a uniform magnitude excitation signal to the elements of said array for permitting maximum power to be delivered to each element of the array, said uniform magnitude excitation signal having a linearly Varying phase deviation for directing the position of the main beam of the radiation pattern, said connecting means being arranged to reverse the phase of the pbase deviated signal to selected ones of the elements that are equidistantly disposed on each side of the center of said array for reducing the side lobes of the yradiation pattern, the total number of said selected ones of said elements being less than 1/10 of the total number of elements in said. array, the distance from the center of said array to any one of said selected ones of said elements being at least 50% of the distance from the center of said array to the edge of said array.

8. A linear array comprising a plurality of elements with approximately 20 elements or more disposed on each side of the center of said array, means for connecting a uniform magnitude excitation signal with a given phase deviation to the elements of said array, said connecting means being arranged to reverse the phase of the phase deviated signal to selected ones of the elements that are equidistantly disposed on each side of 'the center of said array, the total number of said selected ones of said elements being substantially equal to 1/20 of the total number of elements in said array.

9. A linear array comprising a plurality of elements with approximately 20 elements or more disposed on each side of the center of said array, means for connecting a uniform magnitude excitation signal with a given phase deviation to the elements of said array, said connecting means being arranged to reverse the phase of the phase deviated signal to selected ones of the elements that are equidistantly disposed on each side of the center of said array, the total number of said selected ones of said elements being substantially equal to 1/20 of the total number of elements disposed on both sides of the center of said array, the distance from the center of said array to any one of said selected ones of said elements being at least 50% of the distance from the center of said array to the edge of said array.

10. A linear array comprising a plurality of elements with approximately 20 elements or more disposed on each side of the center of said array, means for connecting a uniform magnitude excitation signal with a linear phase deviation to the elements of said array, said connecting means being arranged to reverse the phase of the phase deviated' signal to selected ones of the elements that are equidistantly disposed on each side of the center of said array, the total number of said selected ones of said elements being substantially equal to 1/20 of the total number of elementsdisposed on both sides of the center "of said array.

11. A linear array comprising a plurality of elements vwith approximately 2O elements or more disposed on each side of the center of said array, means for connecting a uniform magnitude excitation signal with a linear phase deviation to the elements of said array, said connecting means being arranged to reverse the phase of the phase deviated signal to selected ones of the elements that are equidistantly disposed on each side of the center lof said array, the totalnumber of said selected ones of said elements being substantially equal to 1/20 of the total number of elements disposed on both sides of the center of said array, the distance from the center of said array to any one of said selected ones of said elements being substantially 80% of the distance from the center Y of said array to the edge of said array.

References Cited bythe Examiner UNITED STATES PATENTS References Cited by the'Applicant UNITEDSTATES PATENTS 1,667,792 5/28 Martin. 1,738,522 12/29 Campbell.

" CHESTER L. JUsTUs, Primary Examiner. 

1. AN ARRAY COMPRISING A PLURALITY OF ELEMENTS, MEANS FOR CONNECTING A UNIFORM MAGNITUDE EXCITATION SIGNAL TO THE ELEMENTS OF SAID ARRAY FOR PERMITTING MAXIMUM POWER TO BE DELIVERED TO EACH ELEMENT OF THE ARRAY, SAID UNIFORM MAGNITUDE EXCITATION SIGNAL HAVING A LINEARLY VARYING PHASE DEVIATION FOR DIRECTING THE POSITION OF THE MAIN BEAM OF THE RADIATION PATTERN, SAID CONNECTING MEANS BEING ARRANGED TO REVERSE THE PHASE OF THE PHASE DEVIATED SIGNAL TO SELECTED ONES OF THE ELEMENTS THAT ARE EQUIDISTANTLY DISPOSED ABOUT THE CENTER OF SAID ARRAY FOR REDUCING THE SIDE LOBES OF THE RADIATION PATTERN. 